The minute your data leaves your premises, it’s not your data anymore.
This outage, as well as the subsequent outage with Azure, had nothing to do with where your data lives. This could happen on your own home network as well.
DNS is basically an Internet phone book. Everything on the Internet runs using IP addresses. IP addresses are numerical and not exactly easy to remember for a large number of endpoints, so it’s not like when you were a kid and could remember your home phone number and the numbers of all of your friends. These are longer numbers and due to the sheer number of them (over 4B possible IPv4 addresses alone), a canonical system for organization makes more sense, hence DNS.
DNS works great... until it doesn’t. Over the years we’ve bolted on functionality for DNS such as more recent DNS-over-HTTPS and DNSSEC. As DNS becomes more complex, and the interoperability (recursion) of DNS systems grows, one small blip in the chain causes a massive outage downstream, and we get what we had with AWS and Azure.
The biggest problem, IMO, is that those of us who know DNS very deep and can unravel the Gordian knot it’s become are getting older, and the very fundamental functionality of the Internet as we know is becoming more anachronistic and is less of a concern or point of understanding for upcoming IT engineers. Modern communication and systems engineers aren’t taught the fundamentals in lieu of learning things like nebulous “cloud” technologies. As a result, one small change to a high level system has downstream impacts that even the most ardent UA tester can’t foresee. As those of us who’ve been doing this work for 30+ years start to eye retirement, the next generation is wholly unprepared for comprehending what was left behind, because, well, let’s face it: we were really bad about documenting it.
The Internet is going to become something akin to the Apollo program but much more impactful. All of the brains behind the origins will die off leaving a system where none of the new blood understand how the subordinate components work, and when something big breaks, we’ll likely see a massive outage that may never fully resolve.